Detection of trace elements such as organic contaminants, explosive residues, and
metal ions is an intellectually challenging task in science and engineering. It is also a
topic of increasing importance due to its impact on society and the environment.
Designing molecularly imprinted materials is one of the most promising approaches to
explore sensing and detection applications. “Stimuli-sensitive” polymer materials are
ideal candidates for these imprinted sensors as they are able to respond to changes in their
environment and can be tailored by cross-linking the polymer chains. The responses can
be amplified and transduced into measurable signals due to macromolecular properties
provided by the use of a polymer. The purpose of the research in this project is to
combine organic polymers with inorganic constituents to tailor the binding properties and
the responses of the composite material for detection of metals ions in aqueous solutions.
The research, here, is based on a thermally responsive polymer such as poly(Nisopropylacrylamide)
(PNIPAM), which exhibits a well-known reversible volume phase
transition in aqueous media around approximately 32°C. Combining cross-linked
microgels formed from PNIPAM and its copolymers with gold nanoparticles (GNP)
imparts the composite material with optical properties such as intense visible absorption
due to the unique surface plasmon absorption of these small nanoparticles. The use of
copolymers allows incorporation of functional groups, such as carboxylic acid, that are
potential sites for binding metal ions. Cross-linking of the metal ion binding polymer
imprints the metal ion in the PNIPAM microgel network.
In
this research, design of the composite material was investigated using
copolymers of NIPAM and acrylic acid (AA), copolymers of NIPAM and glycidyl
methacrylate (GMA), and interpenetrating networks of PNIPAM and PAA. A broad
spectrum of polymerization conditions were studied such as changes in cross-linking
density as well as changes in the synthetic procedure. Techniques such as turbidometry,
ultraviolet visible spectroscopy (UV-VIS), transmission electron microscopy (TEM), and
dynamic light scattering (DLS) were employed to characterize the microgels as well as
their composites with GNP. Preliminary investigation of imprinting the microgels with
heavy metal ions such as copper was also performed. The novel polymer-metal
nanocomposites explored here will serve as an important contribution for the current
ongoing research efforts in designing materials in the nano-scale capable of sensing and
detecting metal ions in solution with high selectivity.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-5096 |
| Date | 11 April 2007 |
| Creators | Chaparro, Dayling L. |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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